The present invention relates to an adjustable armrest for a vehicle.
Many vehicles, such as tractors, have armrests which are adjustable in height to accommodate people with different body shapes. For example, an armrest adjustable mechanism is described in U.S. Pat. No. 5,558,404, issued 24 Sep. 1996 to Muzzy et al, and assigned to the assignee of this application. This design includes castings, special injection molded plastic parts, a belt, and hardware. Some of the parts must have tight tolerances, to minimize free-play in the assembly. The belt wraps around a pair of sprockets to keep the sprockets synchronized. The belt is tensioned by a bushing which presses against the belt. The belt is driven by a plastic gear. The gear is moved through a shaft, which is turned by a knob. The knob has a spring inside it, to keep it pushed out. This design results in a complex assembly. To adjust this mechanism, the operator must simultaneously execute complex and unnatural pushing and twisting motions.
Armrests with adjustable mechanisms are found on production tractors manufactured by John Deere, AgCo, Case-IH and Caterpillar. Such adjustment mechanisms tend to be complex, and require parts which have tight tolerances. Some such mechanisms are difficult to adjust. Some such mechanisms may also have loosely fitting parts which generate undesirable noise when a vehicle vibrates as a result of its movement. Some such mechanisms require parts which are expensive, and require expensive tooling to manufacture.